Oxidation of tin



UNITED STATES PATENT OFFICE.

DUDLEY DE ROS, 0F GREENHITHE, ENGLAND.

OXIDATION OF TIN.

No Drawing.

To all whom it may concern:

Be it known that I, DUDLEY on Ros, a subject of the King of GreatBritain, residing at Black Duck Wharf, Greenhithe, in the county ofKent, England, have invented certain new and useful Improvements in andRelating to the Oxidation of Tin, of which the following is aspecification.

This invention refers to improvements in and relating to the oxidationof tin and has for its object to obtain stannic oxid in an economical,simple and expeditious manner.

The process to which the invention relates is that in which the tin isheated to a temperature at which stannic oxid is formed, air, oxygen orother suitable gas or gaseous mixture, preferably heated being thenblown into or on to the molten tin, with the result that exothermicaction is set up in the molten mass.

According to this invention, the further heating for the continuance ofthe process is performed by the exothermic action alone, furtheradditions of metal being made from time to time to maintain a more orless uniform level and so that it is possible to conduct the process inthis continuous and self contained manner.

A suitable method of carrying the-invention into eifect consists inplacing the metal in an appropriate deep vessel, such as a crucible, potor bath, made of or lined with refractory material and a flame from anoil burner is caused to play upon the crucible or on the surface of themetal contained therein, until the metal is brought to a temperature atwhich stannic oxid is formed, say 1000 C. The flame is then shut off andair, suitably pre-heated to allow temperature by the waste gases fromthe oil burner and thereafter by the oxid given off, is blown into or onto the molten mass, but, preferably, below the surface thereof.Exothermic action then commences, the temperature of the molten metal isconsiderably raised and dense fumes are given off, containing orconsisting of stannic oxid. These fumes are then passed into condensersand the stannio oxid is collected in known manner.

Additional metal preferably heated by the surplus or waste heat from theexothermic reaction is added from time to time in order to maintain amore or less uniform level of the molten metal.

The reason for heating the air supplied to Specification of LettersPatent.

Patented Dec. 14, 1920.

Application filed August 9, 1920. Serial No. 402,357.

produce the exothermic action and for heating the metal to be addedresides in the fact that any undue lowering of the temperature of themolten metal tends to cause the formation of stannous oxid in lieu ofstannic oxid or to reduce the output.

Instead of using liquid fuel, it will be understood that any otherappropriate means of heating may be employed such as solid or gaseousfuel, or an electric furnace, consisting, for example, of an electricresistance in or outside of the crucible or bath, for containing themolten metal or submerged in the molten metal itself.

I claim 1. The method of making tin oxid, which comprises heating a bodyof tin to oxidizing temperature, then discontinuing the heating andsupplying a gaseous oxidant thereto, thereafter continuing the oxidationunder the exothermic reaction conditions so that volatilized stannicoxid is given off, and finally condensing said oxid.

2. The method of making tin oxid, which comprises heating a body of tinto oxidizing temperature sufiicient to melt the tin, then discontinuingthe heating and supplying a gaseous oxidant into the body of the moltentin, thereafter continuing the oxidation under the exothermic reactionconditions so that volatilized stannic oxid is given OE, and finallypassing said volatilized oxid to condensers.

3. The method of making tin oxid, which comprises heating a body of tinto oxidizing temperature, then discontinuing the heating and supplying agaseous oxidant thereto, thereafter continuing the oxidation under theexothermic reaction conditions so that volatilized stannic oxid is givenofi in the form of fume, condensing said volatilized oxid and preheatingthe oxidant by the waste gases of initial heating and by the fumeemanating from the molten tin.

4:. The method of making tin oxid, which comprises heating a body of tinto oxidizing temperature, then discontinuing the heating and supplying agaseous oxidant thereto, thereafter continuing the oxidation under theexothermic reaction conditions so that volatilized stannic oxid is given01f, condensing said volatilized oxid and preheating subsequentadditions of metal by the waste gases and fume.

. DUDLEY DE ROS.

